Feedthrough assembly including sleeve and methods related thereto

ABSTRACT

A feedthrough assembly is disposable in an aperture of, for example, a power source encasement. In various examples, the feedthrough assembly comprises a ferrule, an insulator, a terminal conductor, and a sleeve. A portion of the terminal conductor extends through the ferrule thereby creating a portion internal to and a portion external to the encasement. The insulator is disposed within the ferrule and is sealably engaged with the terminal conductor portion extending through the ferrule. The sleeve is disposed over the internal portion of the terminal conductor and coupled thereto. In one example, the sleeve includes at least one notch on a sleeve first end or a sleeve second end, which may be used to weld or solder the sleeve to the terminal conductor. In another example, the sleeve includes a longitudinally extending void, which may be used to crimp the sleeve to the terminal conductor.

TECHNICAL FIELD

This patent document pertains generally to electrical feedthroughassemblies for use in medical devices, and more particularly, but not byway of limitation, to feedthrough assemblies including a sleeve andmethods related thereto.

BACKGROUND

Numerous applications involve penetrating a sealed encasement (i.e., acontainer) so-as-to provide electrical access to or from electricalcomponents enclosed within. One such application involves bodyimplantable medical devices (referred to as “IMDs”), such as pulsegenerators or cardiac function management devices, for the treatment ofbradycardia, tachyarrhythmia, or muscle or nerve stimulation. One suchexample involves providing electrical access to and from a power source(e.g., a battery) of an IMD.

Electrical feedthrough assemblies provide a conductive path extendingbetween the interior of the (hermetically sealed) encasement and alocation outside the encasement. Typically, the conductive pathcomprises a conductive pin or other type of terminal that iselectrically insulated from the encasement. In addition, feedthroughassemblies may include a ferrule and an insulative material forpositioning and insulating the pin within the ferrule. In the batterypower source example, a conductive connection member is often directlycoupled to an internal portion (i.e., a portion located within thebattery encasement) of the conductive pin on a first end and coupled toan anode or cathode (of the battery) on a second end.

When used in IMDs, feedthrough assemblies need to provide years ofreliable service since maintenance or repair possibilities for thedevices are extremely limited or costly. Moreover, failures of thefeedthrough assembly or components thereof can have catastrophicconsequences as extreme as death for a patient reliant on the IMD.Therefore, feedthrough assemblies need to comprise, among other things,highly reliable components and secure interconnections.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsdescribe substantially similar components throughout the several views.Like numerals having different letter suffixes represent differentinstances of substantially similar components. The drawings illustrategenerally, by way of example, but not by way of limitation, variousembodiments discussed in the present document.

FIG. 1 illustrates a generalized isometric view of an implantablemedical device.

FIG. 2 illustrates a cross-sectional view of a feedthrough assembly andan encasement along line 2-2 of FIG. 1.

FIG. 3A illustrates an isometric view of a sleeve for use in afeedthrough assembly.

FIG. 3B illustrates a cross-sectional view of the sleeve of FIG. 3Aalong line 3B-3B.

FIG. 3C illustrates a cross-sectional view of the sleeve of FIG. 3Aalong line 3C-3C.

FIG. 4A illustrates an isometric view of another sleeve for use in afeedthrough assembly.

FIG. 4B illustrates a cross-sectional view of the sleeve of FIG. 4Aalong line 4B-4B.

FIG. 4C illustrates a cross-sectional view of the sleeve of FIG. 4Aalong line 4C-4C.

FIG. 5A illustrates an isometric view of another sleeve for use in afeedthrough assembly and a portion of a terminal conductor for couplingtherewith.

FIG. 5B illustrates a cross-sectional view of the sleeve of FIG. 5Aalong line 5B-5B.

FIG. 5C illustrates a cross-sectional view of the sleeve of FIG. 5Aalong line 5C-5C.

FIG. 6A illustrates an isometric view of another sleeve for use in afeedthrough assembly and a portion of a conductive connection membercoupled therewith.

FIG. 6B illustrates a cross-sectional view of the sleeve of FIG. 6Aalong line 6B-6B.

FIG. 6C illustrates a cross-sectional view of the sleeve of FIG. 6Aalong line 6C-6C.

FIG. 7A illustrates an isometric view of yet another sleeve for use in afeedthrough assembly.

FIG. 7B illustrates a cross-sectional view along line 7B-7B of FIG. 7A.

FIG. 8 illustrates a method of fabricating a feedthrough assemblycomprising a sleeve.

DETAILED DESCRIPTION

The following detailed description includes references to theaccompanying drawings, which form a part of the detailed description.The drawings show, by way of illustration, specific embodiments in whichthe present assemblies and methods may be practiced. These embodiments,which are also referred to herein as “examples,” are described in enoughdetail to enable those skilled in the art to practice the presentassemblies and methods. The embodiments may be combined, otherembodiments may be utilized, or structural, logical and electricalchanges may be made without departing from the scope of the presentassemblies and methods. The following detailed description is,therefore, not to be taken in a limiting sense, and the scope of thepresent assemblies and methods are defined by the appended claims andtheir legal equivalents.

In this document the terms “a” or “an” are used to include one or morethan one; the term “or” is used to refer to a nonexclusive or unlessotherwise indicated; and the term “subject” is used to include the term“patient.” In addition, it is to be understood that the phraseology orterminology employed herein, and not otherwise defined, is for thepurpose of description only and not of limitation.

Introduction

The present assemblies and methods provide, among other things, aconductive path extending between the interior of an encasement, such asan IMD power source encasement, and a location outside the encasementvia a feedthrough assembly including a sleeve. Use of a sleeve increasesthe connection strength between components of the feedthrough assembly(e.g., a terminal conductor and a conductive connection member). Thisenhances the reliability of the feedthrough assembly and IMDs employingthe same. In addition, a sleeve facilitates manufacturability offeedthrough assembly connections (e.g., by providing a larger connectionsurface area for welding, soldering, or brazing a conductive connectionmember to a terminal conductor) thereby reducing manufacturing costs.These and other aspects, advantages, and features of the presentassemblies and methods will become apparent from a consideration of thefollowing description and associated drawings.

EXAMPLES

In FIG. 1, an example of a generic IMD 100 is illustrated. In thisexample, IMD 100 includes a power source section 102, an electronicssection 104, a capacitor section 106, and one or more feedthroughassemblies 108. The “IMD” will typically include, among other things,cardiac function management (referred to as “CFM”) systems such aspacemakers, cardioverters/defibrillators, paces/defibrillators,biventricular or other multi-site resynchronization or coordinationdevices such as cardiac resynchronization therapy (referred to as “CRT”)devices, or drug delivery systems.

Power source section 102 may include, but is not limited to, anelectrochemical cell, an electrolytic or other capacitor, or a battery.In one example, power source section 102 comprises a battery having ananode or a cathode 202 terminal (FIG. 2) and is enclosed by anencasement 110, such as a can or other container. In the example of FIG.2, encasement 110 includes at least one encasement aperture 204 intowhich the one or more feedthrough assemblies 108 are mounted. Asdiscussed above, feedthrough assembly 108 penetrates the otherwisesealed encasement 110, such as to provide electrical access to or fromone or more electrical components (e.g., an anode or a cathode terminal202) enclosed therewithin.

Notably, FIG. 1 illustrates one example of various sections andassemblies of an IMD 100. Power source section 102, electronics section104, capacitor section 106, and the one or more feedthrough assemblies108 are illustrated separately for conceptual clarity; however, suchsections and assemblies may be further separated or need not beseparately embodied.

FIG. 2 illustrates a cross-sectional view 200, such as along line 2-2 ofFIG. 1, of an example of a single-terminal feedthrough assembly 108 anda (battery) encasement 110 into which feedthrough assembly 108 providesaccess to or from. In this example, encasement 110 includes at least oneaperture 204 into which feedthrough assembly 108 is mounted. In variousexamples, feedthrough assembly 108 is coupled to a wall surface ofaperture 204, such as via (laser or resistance) welding, soldering,brazing, gluing, or any other suitable connection technique known in theart.

In the example of FIG. 2, feedthrough assembly 108 includes a ferrule212, an insulator member or body 214 contacting ferrule 212, a terminalconductor (e.g., a conductor pin) 206 with a length 208 portionextending through an opening 210 in ferrule 212, and a sleeve 216. Byidentifying a portion of its length 208 as extending through opening210, terminal conductor 206 may be conceptualized as having an internalportion 218 extending into the interior of encasement 110 and anexternal portion 220 extending out of encasement 110. Using one or moreof a variety of techniques, as further discussed below, sleeve 216 isaffixed to internal portion 218 of terminal conductor 206, such as toincrease the strength or reliability of one or more connections madethereto, such as by a conductive connection member 222.

In the example of FIG. 2, insulator member or body 214 surrounds atleast a portion of the length 208 of the terminal conductor 206extending through opening 210. In one example, insulator 214 comprises aglass such as sapphire; however, the present assemblies and methods arenot so limited. Insulator member or body 214 can be made of any suitableceramic-containing material or other electrically-insulative materialsuch as diamond, ruby, zinc oxide, or even one or more high dielectricpolymers such as one or more polyimides. Among other utilities,insulator member or body 214 prevents a short circuit from occurringbetween terminal conductor 206 and ferrule 212 or encasement 110.

In order to ensure a tight seal between insulator member or body 214 andthe walls of encasement 110 or encasement aperture 204, ferrule 212 maybe disposed as a (thin) sleeve therebetween. Among other things, ferrule212 provides a support for insulator 214 and terminal conductor 206 or ameans for mounting feedthrough assembly 108 in encasement 110, such asvia welding, soldering, brazing, gluing, or any other suitableconnection. Ferrule 212 is typically annular; however, ferrule 212 mayhave any other configuration suitable for use with encasement 110.Ferrule 212 may comprise any material or combination of materials knownin the art to be suitable for providing support for insulator 214 andterminal conductor 206 or providing a means for mounting feedthroughassembly 108 in encasement 110.

Electrical feedthrough assemblies 108 that are used in, for example,body IMDs may potentially come in contact with bodily fluids. Thus, itis desirable that components of feedthrough assembly 108, such asterminal conductor 206, comprise bio-stable, non-corrosive materials.Terminal conductor 206 may comprise one or more of molybdenum, titanium,tantalum, platinum, iridium, zirconium, aluminum, stainless steel,nitrides of such metals, alloys of such metals, or one or more otherbio-stable metals. In one example, terminal conductor 206 comprisesmolybdenum, which has a coefficient of thermal expansion (referred to as“CTE”) similar to the CTE of an insulator 214 comprising glass. Bysubstantially matching the CTE of insulator 214 with the CTE of terminalconductor 206, insulator 214 (e.g., glass) does not crack when it coolsfrom an elevated temperature.

As discussed above, feedthrough assembly 108 comprises a sleeve 216coupled to the internal portion 218 of terminal conductor 206. Sleeve216 allows for, among other things, a more secure connection to beestablished between terminal conductor 206 and one or more componentswithin encasement 110, such as an anode or cathode 202 of a battery. Inparticular, sleeve 216 allows for a more secure connection to beestablished between terminal conductor 206 and a conductive connectionmember 222 (e.g., a conductive ribbon), the latter of which linksterminal conductor 206 to anode or cathode 202. Although not shown,anode and cathode 202 are typically separated by a separator, such as anion-permeable separator.

Experimental tests have shown that pull-strengths of the connectionbetween terminal conductor 206 and conductive connection member 222greatly increase when a sleeve 216 is used in the connection scheme. Forexample, according to one test, the pull-strength of a terminalconductor 206/conductive connection member 222 connection using a sleeve216 was found to be more than double that which was found when sleeve216 was not used in the connection (i.e., when conductive connectionmember 222 was coupled directly to an outer surface of terminalconductor 206). Besides increased pull-strength, use of sleeve 216 mayalso advantageously help avoid connection failure or improve the mode bywhich connection failure occurs. As one example, use of sleeve 216allows for force distribution on terminal conductor 206 in a manner thatimproves the fatigue resistance of the connection (i.e., the connectionbetween terminal conductor 206 and conductive connection member 222).

Yet another advantage of sleeve 216 is that it can effectively changethe material compositions of feedthrough assembly 108 components to becoupled. As one example, if terminal conductor 206 is composed of afirst material and conductive connection member 222 is composed of asecond material that is not easily weldable or otherwise couplable tothe first material, sleeve 216 (composed of a material more compatiblewith the second material) may be crimped (or otherwise attached) toterminal conductor 206 thereby effectively changing the materialcomposition of terminal conductor 206 (as far as conductive connectionmember 222 is concerned) to that of sleeve 216. Sleeve 216 may comprisestainless steel, aluminum, titanium, or any other material compatiblewith the particular battery chemistry.

FIGS. 3A-3C, 4A-4C, 5A-5C, 6A-6C, and 7A-7B illustrate various examplesof sleeve 216 structures that may be used, such as to facilitate orstrengthen a connection between a terminal conductor 206 (FIG. 2) and aconductive connection member 222 (FIG. 2). Sleeve 216 may be affixed toterminal conductor 206, such as via welding (see FIGS. 3A-3C), soldering(see FIGS. 3A-3C), brazing (see FIGS. 3A-3C), crimping (see FIGS.4A-4C), or swaging (see FIGS. 5A-5C) techniques. In certain examples,sleeve 216 includes one or more notches 302, longitudinally-extendingnotches or voids 402, swage projections 502, flat portions 602, orintroductory openings 702, such as to facilitate insertion of terminalconductor 206 within sleeve 216, attachment of sleeve 216 and terminalconductor 206, or positioning of sleeve 216 with respect to terminalconductor 206.

Sleeve 216 need not be specifically extruded during manufacture, butrather can be stock (off-the-shelf) tube or pipe, thereby reducingmanufacturing costs (as compared with specifically extruded sleeves). Invarying examples, a length 304 of sleeve 216 is sufficient to surroundat least a portion of an internal portion 218 (FIG. 2) of terminalconductor 206. In one example, length 304 of sleeve 216 is 0.055 inches.In another example, length 304 of sleeve 216 is 0.070 inches. In varyingexamples, an inner diameter 306 of sleeve 216 is slightly larger than anouter diameter of terminal conductor 206. In one example, inner diameter306 of sleeve 216 is 0.016 inches while an outer diameter 308 of sleeve216 is 0.028 inches.

The example of sleeve 216 shown in FIGS. 3A-3C includes one or morenotches 302, which may be used for the positioning of sleeve 216relative to terminal conductor 206 or for connection between suchcomponents. In one example, notch 302 is used to (laser or resistance)weld, solder, or braze sleeve 216 to terminal conductor 206. In thisexample, notch 302 extends inward from a sleeve end face 310 and has asize of 0.016 inches×0.016 inches. In another example, notch 302 has asize of 0.012 inches×0.012 inches. Similarly, sleeve 216 may include atleast one notch 302 extending inward from each sleeve end face 310.

The example of sleeve 216 shown in FIGS. 4A-4C includes alongitudinally-extending void 402, which may be used to couple sleeve216 to terminal conductor 206, such as via crimping forces.Longitudinally-extending void 402 allows sleeve crimp faces 404 to movetoward one another when a crimping force is applied to an outer surfaceof sleeve 216. As crimp faces 404 move closer to one another, innerdiameter 306 of sleeve 216 is effectively reduced thereby increasingpress-fitting forces experienced by an outer surface of terminalconductor 206 and inner surface of sleeve 216.

FIGS. 5A-5C illustrate an example of sleeve 216 including one or moreswage projections 502 and an internal portion 218 (FIG. 2) of a terminalconductor 206. In this example, internal portion 218 includes one ormore grooves 504 into which portions of sleeve 216 may be deformed. Inone example, after sleeve 216 is disposed over internal portion 218, thesleeve may be deformed, such as by rotary swaging (a metal formingprocess for the diametrical reduction of annular members, such astubes). In this example, rotary swaging of sleeve 216 provides an inwardforce on swage projections 502 causing the shape of sleeve 216 to deforminto grooves 504. As a result, sleeve 216 becomes affixed to terminalconductor 206.

FIGS. 6A-6C illustrate an example of sleeve 216 including a flat portion602 extending the entire length 304 of the sleeve. Coupled to flatportion 602 is a first end of a conductive connection member 222. Anopposing second end of connection member 222 may be attached to, forexample, an anode or a cathode 202 of a battery. In this example,conductive connection member 222 comprises a stainless steel or otherconductive ribbon. Flat portion 602 permits good surface contact withconductive ribbon 222, thereby allowing a solid weld or other couplingtherebetween.

The sleeve 216 in the example of FIGS. 7A-7B includes an introductoryopening 702, which facilitates the insertion of a terminal conductor 206(FIG. 2) into the sleeve. As shown in the example of FIG. 7B, an openingdiameter 704 of introductory opening 702 is greater than a diameter 506(FIG. 5A) of an internal portion 218 of terminal conductor 206. In thisexample, introductory opening 702 continuously narrows or otherwisetapers to a diameter slightly larger than diameter 506 but smaller thanopening diameter 704, thereby guiding terminal conductor 206 withinsleeve 216.

FIG. 8 is a flow diagram illustrating a method 800 of fabricating afeedthrough assembly including a sleeve. At 802, a ferrule including aferrule aperture is provided. At 804, a portion of a terminal conductor(e.g., a terminal pin) is inserted through the ferrule aperture suchthat when the ferrule is mounted in an aperture of an encasement (at814), one end of the terminal conductor extends into an interior of theencasement and makes contact with a desired portion of the contentsthereof, and the other end extends exteriorly of the encasement. At 806,a portion of the terminal conductor disposed within the ferrule apertureis surrounded by an insulator member or body (e.g., glass). In oneexample, surrounding the terminal conductor with the insulator includessealably engaging the insulator with the terminal conductor to preventany (e.g., electrolyte) leakage between such components.

At 808, a sleeve for attachment to the internal portion of the terminalconductor is selected. The sleeve may (but need not) contain notches,windows, chamfers, terminal conductor guidance cavities, or other voidsor configurations, such as to facilitate overlapping, positioning, orattaching of the sleeve on or to the terminal conductor. At 810, theinternal portion of the terminal conductor is inserted into the selectedsleeve. In one example, insertion of the terminal conductor into thesleeve includes using a tapered introductory cavity (e.g., afunnel-shaped configuration) integrated with a sleeve first end.

At 812, the selected sleeve is (electrically) connected to the internalportion of the terminal conductor. In one example, connection of thesleeve to the terminal conductor includes (laser or resistance) welding,soldering, or brazing of the sleeve to the terminal conductor. Inanother example, connection of the sleeve to the terminal conductorincludes crimping of the sleeve onto the terminal conductor. In yetanother example, connection of the sleeve to the terminal conductorincludes deformation (e.g., via rotary swaging) of the sleeve into oneor more groove of the terminal conductor. In a further example,connection of the sleeve onto the terminal conductor includes heatingthe sleeve such that it expands, then placing the sleeve onto theterminal conductor, and finally allowing the sleeve to (compressively)cool onto the terminal conductor.

As discussed above, the feedthrough assembly is mountable in an apertureof an encasement, such as an electrical power source encasement, whichoccurs at 814. In one example, the feedthrough assembly is mounted inthe aperture via welding, soldering, brazing, or through the use of anadhesive. At 816, a first end of the conductive connection member iscoupled to the sleeve and a second end of the connection member iscoupled to an anode or a cathode of an electrical power source battery.In one example, the conductive connection member includes a stainlesssteel ribbon which is welded to an internal portion of the sleeve on afirst end and to the anode or cathode on a second end.

CONCLUSION

Feedthrough assemblies and methods for their manufacture are providedherein. Among other things, the present assemblies and methods provide afeedthrough assembly including a connection-facilitating sleeve. Thesleeve increases the strength and fatigue resistance of interconnectionsbetween feedthrough components (e.g., the terminal conductor andconductive connection member). This enhances reliability of thefeedthrough assembly and IMDs employing the same. In addition, use ofthe sleeve improves the manufacturability of feedthrough assemblies, asa greater (more robust) surface area is available for electricalcoupling (e.g., welding, soldering, or brazing) between the conductiveterminal and conductive connection member.

The present assemblies and methods are not limited to feedthroughs forbatteries, but extend to other IMD or like applications where it isdesired to penetrate a sealed encasement (i.e., a container), such as toprovide electrical access to and from electrical components enclosedwithin. It will also be appreciated by those skilled in the art thatwhile a number of specific dimensions or method orders are discussedabove, the present assemblies can be made of any size (e.g., lengths,widths, or diameters) and may be fabricated in method orders other thanthose discussed.

It is to be understood that the above description is intended to beillustrative, and not restrictive. For example, the above-describedembodiments (and/or aspects thereof) may be used in combination witheach other. Many other embodiments will be apparent to those of skill inthe art upon reviewing the above description. The scope of the presentassemblies and methods should, therefore, be determined with referenceto the appended claims, along with the full scope of equivalents towhich such claims are entitled. In the appended claims, the terms“including” and “in which” are used as the plain-English equivalents ofthe respective terms “comprising” and “wherein.” Also, in the followingclaims, the terms “including” and “comprising” are open-ended, that is,a system, device, article, or process that includes elements in additionto those listed after such a term in a claim are still deemed to fallwithin the scope of that claim. Moreover, in the following claims, theterms “first,” “second,” and “third,” etc. are used merely as labels,and are not intended to impose numerical requirements on their objects.

The Abstract of the Disclosure is provided to comply with 37 C.F.R. §1.72(b), requiring an abstract that will allow the reader to quicklyascertain the nature of the technical disclosure. It is submitted withthe understanding that it will not be used to interpret or limit thescope or meaning of the claims. In addition, in the foregoing DetailedDescription, various features may be grouped together to streamline thedisclosure. This method of disclosure is not to be interpreted asreflecting an intention that the claimed embodiments require morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter may lie in less thanall features of a single disclosed embodiment. Thus the following claimsare hereby incorporated into the Detailed Description, with each claimstanding on its own as a separate embodiment.

1. An implantable medical device comprising: an encasement having atleast one aperture therethrough; an electrical power source in theencasement configured to provide power to electrical circuitry of theimplantable medical device; a feedthrough assembly at least partiallypositioned in the encasement aperture, the feedthrough assemblycomprising, a terminal conductor at least partially passing through theencasement aperture and extending from an internal portion disposedwithin the encasement to an external portion disposed outside theencasement, the terminal conductor including an outer surface; aninsulator disposed within at least a portion of the encasement apertureand surrounding at least a portion of the terminal conductor extendingthrough the encasement aperture; and a sleeve extending from a sleevefirst end to a sleeve second end and having a sleeve intermediateportion therebetween, the sleeve including an inner surface engagedagainst the outer surface of the internal portion of the terminalconductor from near the sleeve first end to at least a midpoint of thesleeve substantially half way between the sleeve first end and thesleeve second end; and a conductive connection member physicallyconnected and electrically coupled to an outer surface of the sleeve,wherein the conductive connection member laterally approaches andlaterally physically contacts the outer surface of the sleeve; whereinthe feedthrough assembly provides a conductive path extending between aninterior of the encasement and a location outside of the encasement. 2.The implantable medical device as recited in claim 1, wherein theconductive connection member is electrically coupled to the sleeve at amember first end portion and electrically coupled to the electricalpower source at a member second end portion.
 3. The implantable medicaldevice as recited in claim 2, wherein one or both of the sleeve or theconductive connection member comprise stainless steel.
 4. Theimplantable medical device as recited in claim 2, wherein the outersurface of the sleeve includes a substantially flat portion to engageagainst a portion of a substantially flat conductive connection member.5. The implantable medical device as recited in claim 4, wherein thesubstantially flat portion extends from near the sleeve first end tonear the sleeve second end.
 6. The implantable medical device as recitedin claim 1, wherein the sleeve includes at least one weld or soldernotch at one or both of the sleeve first end or the sleeve second end.7. The implantable medical device as recited in claim 6, wherein the atleast one weld or solder notch includes a dimensional length of at least0.012 inches.
 8. The implantable medical device as recited in claim 1,wherein the sleeve includes a longitudinally extending void; andcomprising a crimp securing the sleeve to the outer surface of theterminal conductor, the crimp occurring by way of the longitudinallyextending void.
 9. The implantable medical device as recited in claim 1,wherein the internal portion of the terminal conductor includes one ormore grooves extending inward from the outer surface thereof; andwherein the sleeve is configured to be deformable into the one or moregrooves.
 10. The implantable medical device as recited in claim 1,wherein the sleeve first end includes an introductory opening having afirst diameter, the first diameter narrowing to a diameter larger thanthe outer diameter of the terminal conductor at or near the sleeveintermediate portion or the sleeve second end.
 11. The implantablemedical device as recited in claim 1, wherein the terminal conductorcomprises molybdenum.
 12. The implantable medical device as recited inclaim 1, wherein a length of the sleeve as measured from the sleevefirst end to the sleeve second end is at least about 0.055 inches. 13.The implantable medical device as recited in claim 1, wherein the innersurface of the sleeve is engaged against the outer surface of theterminal conductor from near the sleeve first end to near the sleevesecond end.
 14. The implantable medical device as recited in claim 1,wherein the sleeve is configured to laterally surround the internalportion of the terminal conductor from near the sleeve first end to nearthe sleeve second end.
 15. The implantable medical device as recited inclaim 1, wherein the sleeve comprises at least one of stainless steel,aluminum, or titanium.
 16. The implantable medical device as recited inclaim 1, wherein the terminal conductor comprises at least one oftitanium, tantalum, platinum, iridium, zirconium, aluminum, or stainlesssteel.
 17. The implantable medical device as recited in claim 1, whereinthe terminal conductor comprises a material having a coefficient of thethermal expansion substantially the same as a coefficient of the thermalexpansion of the insulator.
 18. An implantable medical devicecomprising: an encasement having at least one aperture therethrough; anelectrical power source in the encasement configured to power toelectrical circuitry of the implantable medical device; a feedthroughassembly at least partially positioned in the encasement aperture, thefeedthrough assembly configured to provide a conductive path extendingbetween an interior of the encasement and a location outside of theencasement, the feedthrough assembly comprising, an insulator disposedwithin a portion of the encasement aperture; a terminal conductorextending through the insulator, the terminal conductor having aninternal portion disposed within the encasement and an external portiondisposed outside of the encasement, the internal and external portionsseparated by a terminal conductor portion positioned within theinsulator; a sleeve extending from a sleeve first end to a sleeve secondend, the sleeve including an inner surface directly coupled to an outersurface of the internal portion of the terminal conductor from near thesleeve first end, through a midpoint of the sleeve substantially halfway between the sleeve first end and the sleeve second end, to near thesleeve second end; and a conductive connection member physicallyconnected and electrically coupled to an outer surface of the sleeve,wherein the conductive connection member laterally approaches andlaterally physically contacts the outer surface of the sleeve.
 19. Theimplantable medical device as recited in claim 18, comprising a ferrulein contact with the encasement on an outer ferrule surface and incontact with the insulator on an inner ferrule surface.
 20. Theimplantable medical device as recited in claim 18, wherein the sleeveincludes at least one notch extending from one or both of the sleevefirst end or the sleeve second end.
 21. The implantable medical deviceas recited in claim 20, comprising a weld or solder configured to securethe sleeve to the outer surface of the terminal conductor; and whereinthe weld or solder is disposed adjacent the at least one notch.
 22. Theimplantable medical device as recited in claim 18, wherein the sleeveincludes a longitudinally extending void; and comprising a crimpsecuring the sleeve to the outer surface of the terminal conductor, thecrimp occurring by way of the longitudinally extending void.
 23. Theimplantable medical device as recited in claim 18, wherein the internalportion of the terminal conductor includes one or more grooves extendinginward from the outer surface thereof; and wherein the sleeve isconfigured to be deformed into the one or more grooves.
 24. Theimplantable medical device as recited in claim 18, wherein the outersurface of the sleeve is electrically coupled to one of a cathodeassembly or an anode assembly of the electrical power source; and theinner surface of the sleeve is electrically engaged with the internalportion of the terminal conductor.
 25. The implantable medical device asrecited in claim 18, wherein the conductive connection member includes amember first end electrically coupled to the outer surface of the sleeveand a member second end electrically coupled to one of the cathodeassembly or the anode assembly.
 26. The implantable medical device asrecited in claim 25, wherein the outer surface of the sleeve isconfigured to mate with a portion of the conductive connection member.27. The implantable medical device as recited in claim 25, comprising aweld between the outer surface of the sleeve and the conductiveconnection member.